Amazonian Savanna Research Articles

Structure and tree species composition in different habitats of savanna used by indigenous people in the Northern Brazilian Amazon.

BackgroundWoody plant diversity from the Amazonian savannas has been poorly quantified. In order to improve the knowledge on wood plants of these regional ecosystems, a tree inventory was carried out in four different habitats used by indigenous people living in the savanna areas of the Northern Brazilian Amazon. The habitats were divided into two types (or groups) of vegetation formations: forest (riparian forest, forest island, and buritizal = Mauritia palm formation) and non-forest (typical savanna). The inventory was carried out in two hectares established in the Darora Indigenous Community region, north of the state of Roraima.New informationThe typical savanna is the most densely populated area (709 stems ha-1); however, it has the lowest tree species richness (nine species, seven families) in relation to typical forest habitats: riparian forest (22 species, 13 families and 202 stems ha-1), forest islands (13 species, 10 families and 264 stems ha-1), and buritizal (19 species, 15 families and 600 stems ha-1). The tree structure (density and dominance) of the forest habitats located in the savanna areas studied in this work is smaller in relation to forest habitats derived from continuous areas of other parts of the Amazon. These environments are derived from Paleoclimatic fragmentation, and are currently affected by the impact of intensive use of natural resources as timberselective logging and some land conversion for agriculture.

Seed dispersal by macaws shapes the landscape of an Amazonian ecosystem

Seed dispersal is one of the most studied plant–animal mutualisms. It has been proposed that the dispersal of many large-seeded plants from Neotropical forests was primarily conducted by extinct megafauna, and currently by livestock. Parrots can transport large fruits using their beaks, but have been overlooked as seed dispersers. We demonstrate that three macaws (Ara ararauna, A. glaucogularis and A. severus) are the main dispersers of the large-seeded motacú palm Attalea princeps, which is the biomass-dominant tree in the Bolivian Amazonian savannas. Macaws dispersed fruits at high rates (75–100% of fruits) to distant (up to 1200 m) perching trees, where they consumed the pulp and discarded entire seeds, contributing to forest regeneration and connectivity between distant forests islands. The spatial distribution of immature palms was positively associated to the proximity to macaws’ perching trees and negatively to the proximity to cattle paths. The disperser role of livestock, presumably a substitute for extinct megafauna, had little effect due to soil compaction, trampling and herbivory. Our results underscore the importance of macaws as legitimate, primary dispersers of large-seeded plants at long distances and, specifically, their key role in shaping the landscape structure and functioning of this Amazonian biome.

Use and traditional knowledge of Byrsonima crassifolia and B. coccolobifolia (Malpighiaceae) in a Makuxi community of the Roraima savanna, northern Brazil

ABSTRACT Byrsonima crassifolia and B. coccolobifolia, popularly known as mirixis, muricis, mantecos or nances, are common fruit species in the Amazonian savannas. Their fruits are used in the preparation of juices and other beverages, while the other parts of the plants are used for different purposes in some indigenous communities. The aim of the present ethnobotanical study was to investigate the knowledge and traditional uses of mirixis in the Darora Indigenous Community, of the Makuxi ethnicity, in the São Marcos Indigenous Land, state of Roraima, northern Brazil. The knowledge on these species among the residents was analyzed considering their gender and age. A survey was carried out by means of semi-structured interviews with 60 respondents (36 men and 24 women), between 18 and 84 years of age. Data from the interviewees was compared between genders and two age groups (< 40 and ≥ 40 years of age). Ethnobotanical indices (Informant diversity value; Informant equability value) were calculated, and no significant differences were found in the diversity of uses between genders (U = 283.0000, p > 0.05) and age groups (U = 359.5000, p > 0.05), indicating that the knowledge on the species is evenly distributed among residents. Results show that both species are used for different purposes in the food, fuelwood and medicinal categories in the Darora Community, and this knowledge is widely shared among adult men and women of all ages.

Amphibians found in the Amazonian Savanna of the Rio Curiaú Environmental Protection Area in Amapá, Brazil

Abstract Amphibian research has grown steadily in recent years in the Amazon region, especially in the Brazilian states of Amazonas, Pará, Rondônia, and Amapá, and neighboring areas of the Guiana Shield. Even so, few data are available for the Amazonian savannas of Brazil. To contribute to the understanding of the diversity of the amphibians of these savannas, we surveyed 15 temporary ponds, six located in open areas, seven on the edge of savanna forest, and two within the forest, in the savanna of the Rio Curiaú Environmental Protection Area (EPA) in Macapá, in the state of Amapá, northern Brazil. Sampling occurred from May 2013 to August 2014 during periods when the ponds contained water. Amphibians were sampled through visual and auditory surveys conducted during both the day- and the nighttime periods on seven days each month over a total of 84 days. A total of 1574 individuals belonging to four families, 12 genera, and 28 species were recorded during the surveys. The cumulative species curve reached the asymptote, indicating that sampling effort was adequate. The number of species was 25% higher than that reported in other studies in Amazonian savannas. Twelve species were recorded for the first time in the savanna of Amapá. Lysapsus boliviana was the most common species (n = 332 of the individuals recorded). The greatest amphibian species richness found in the Rio Curiaú EPA was associated with the savanna mosaic, forest patches, lowland swamp, and temporary ponds. The results of this study contribute to the understanding of the diversity of amphibian species in the Guianan area of endemism in northern Brazil, and also the Amazonian savannas.

A reassessment of the vocalization and distribution of Scinax exiguus (Duellman, 1986) (Anura: Hylidae) in the Amazonian savanna of Roraima, northern Brazil, with the description of its aggressive call

Scinax exiguus was described from the Gran Sabana, southeastern Venezuela, and its distribution is associated with the one Amazonian savanna region in northern South America. Herein, we describe the aggressive call and redescribe the advertisement call of S. exiguus, including recordings from the type locality. Also, we report on intraspecific variation between Venezuelan and Brazilian populations and we make remarks on its distribution in Brazil. Advertisement calls from the type locality (Bolívar, Venezuela) mainly differ in temporal traits from those of the two Brazilian populations, especially in duration and pulse organization. In contrast, calls from both Brazilian populations had remarkable differences from each other in the dominant frequency. Body size also varied between the type series (Venezuela) and a Brazilian population. We suggest that the acoustic variation in S. exiguus might be explained partly by differences in temperature and varying degrees of motivational state of calling males. One of our study sites (Cantá, Roraima) now represents the southernmost record for the species in comparison to the previous record (Boa Vista). Additional research and conservation measures are required in the Guyanan savanna in northern South America for the protection of its endemics.

The Fate of an Amazonian Savanna: Government Land-Use Planning Endangers Sustainable Development in Amapá, the Most Protected Brazilian State

Although Amapa is the most protected Brazilian state, the same level of protection does not extend to its savannas. These are currently suffering increased pressure from threats including large-sca...

Elucidating adaptive strategies from leaf anatomy: Do Amazonian savannas present xeromorphic characteristics?

This is among the first studies that associate anatomical characteristics to the environment in the transition region between the two largest phytogeographic domains of South America. We aimed to analyze the leaf anatomy of 22 plant species occurring in the Amazonian savanna in the state of Mato Grosso, Brazil, with the purpose of identifying key characters that show adaptive species strategies in their natural environments. Our hypothesis was that species typical of forest habitats would not present xeromorphic characteristics, while species typical of savanna habitats would present such characteristics. We fixed the samples in FAA50,11FAA 50 (Formaldehyde, Acetic acid and ethyl alcohol). that were stored in alcohol 70%, later they were free-hand cut with a razor blade and stained with astra blue and basic fuchsin. For the analysis of the leaf epidermis, we used the Jeffrey modified method of separation. Characteristics such as thick cuticle, epidermis with thickened wall and straight, presence of silica in the epidermis, tector trichomes, hypostomatic leaves, stomatic crests, dorsiventral mesophyll, presence of collenchyma and vascular bundles were associated with adaptive strategies of the plants to the environment of Amazonian savanna. The anatomic characters presented here are of great importance for the species that live in savanna environments, demonstrating plasticity and contributing to the protection of the leaves to the diverse biotic and abiotic factors to which they are subject, ensuring thus the survival of the species. We demonstrate that plant species structure of Amazonian savanna is most likely shaped by environment determinism, and this fact has implications on how we expect such plants evolve in a climate changing world.

What is the avifauna of Amazonian white-sand vegetation?

SummaryWhite-sand vegetation (WSV) is a rare vegetation type in the Amazon basin that grows in nutrient impoverished sandy soils that occur as patches of variable size. Associated with this vegetation is bird assemblage that has not yet been fully characterized. Based on published species inventories and our own field data we compile a checklist of bird species recorded in WSV. In addition, we compared the avifauna of WSV with that found in savanna patches, another type of Amazonian open vegetation. WSV hosted a distinctive avifauna including endemic and threatened species. The number of bird species was lower in WSV compared to nearby terra firme forests, seasonally flooded forests and Amazonian savannas. Despite its low diversity, the avifauna of WSV has a distinctive species composition and makes a significant contribution to Amazonian beta diversity. At least 35 bird species can be considered as indicator species for this environment. Previously identified areas of endemism within the Amazon basin house at least one WSV indicator bird including cases of congeneric species with allopatric distributions. Seven of the WSV indicator species (20% of this avifauna) are in an IUCN threatened category, with one speciesPolioptila clementsiconsidered Critically Endangered. Their isolated distribution, small area occupied, and fragility to human-driven disturbances makes WSV one of the most threatened vegetation types in the Amazon basin. The study of WSV avifauna contributes to a better understanding of mechanisms that generate and maintain species diversity as well as of the environmental history of the most biologically diverse biome of the planet.

Parrots as overlooked seed dispersers

Parrots as overlooked seed dispersers

Composition and ecological patterns of snake assemblages in an Amazon-Cerrado Transition Zone in Brazil

ABSTRACT The present study encompasses the species composition and ecological characteristics of the snake community in a Cerrado-Amazon transition zone in Midwest of Brazil (state of Mato Grosso). The data were collected during six excursions to the "Tanguro" (study area) by visual encounter survey, pitfall traps with drift fences and non-systematic sampling. We collected 194 specimens, distributed in 34 species, 26 genera, and eight families. The most abundant species were Crotalus durissus Linnaeus, 1758 (n = 50), Philodryas olfersii (Lichtenstein, 1823) (n = 15), Philodryas nattereri Steindachner, 1870 (n = 13), Xenodon rabdocephalus (Wied, 1824) (n = 12), Lachesis muta (Linnaeus, 1766) (n = 10) and Erythrolamprus almadensis (Wagler, 1824) (n = 10). The composition of species found here represents a combination of Cerrado and Amazonian savanna fauna.

Core and transient species in an Amazonian savanna bird assemblage

In this paper, we report the number of core and transient bird species in an Amazonian savanna site and assess their ecological differences. We conducted our study at Campo Experimental do Cerrado (CEC) da Embrapa–Amapa, 48 km north of Macapa (0 2'5 N / 51 2'2 W), Amapa, Brazil. Forty points were monitored on a monthly basis over the course of one year, using the unlimited-distance point counts in a plot of 360 hectares of well-preserved and relatively homogeneous upland savanna from September 2006 to August 2007. Species were classified in core (recorded in the area in nine or more months), transient (recorded in the area in four or less months) and intermediate (the ones recorded between five and eight months). Species were also classified according to feeding guilds and habitat preferences. Statistical analyses were made to compare core and transient species. We recorded 72 species in the plot, of which 36 were transients, 12 were intermediates, and 22 were core. Core species have higher abundances than transient species. Core species are found mostly in the savanna while transient species also occur in other habitats within the landscape. Both core and transient groups presented well-marked seasonal variation in abundance. Recruitment explains abundance variation for core species, while differences in the availability of food resources in the site explains variation of the abundance in transient species. We predict that plot-level (not more than 500 hectares) bird assemblages in South American savannas will be composed of a small number of abundant and habitat-restricted species that occupy the site almost year round, combined with a high number of low abundant transient species that are habitat generalists and use the plot only during limited periods of their annual life cycle.

The role of remnants of Amazon savanna for the conservation of Neotropical mammal communities in eucalyptus plantations

In this study, we investigated the effects of the partial conversion of native Amazon savanna into a eucalyptus plantation on the richness, composition, and abundance of medium and large mammals. Considering these plantations as an integral component of a patchwork savanna landscape, we verified how the negative effects of these plantations can be buffered by the conservation of remnants of native habitat within their area. We analyzed the contribution of each type of Amazonian savanna to the maintenance of the mammalian fauna and the potential of eucalyptus plantations to substitute these native habitats. A total of 23 mammal species were recorded in line-transect surveys conducted within the conserved savanna. By contrast, only eight species were recorded in the eucalyptus plantation and none of them were exclusive to this vegetation. However, the landscape patchwork formed by plantations and savanna was more diverse and contained 19 species of mammals, highlighting the potential importance of remnant savanna vegetation. The maintenance of remnants of savanna habitat may thus be essential for ensuring the conservation of mammals in the anthropogenic landscape of this region. It will also be important to include as many different subtypes of native savanna vegetation as possible and to consider the connectivity between habitats.

Fatores edáficos determinando a ocorrência de leguminosas herbáceas em savanas amazônicas

Fatores edáficos vem sendo indicados como determinantes para a distribuição de comunidades de plantas na Amazônia. O objetivo deste estudo foi investigar quais fatores edáficos determinam a ocorrência de leguminosas herbáceas em savanas amazônicas. Para tanto, foi realizado um inventário da flora herbácea da família Leguminosae em 34 parcelas permanentes estabelecidas em duas áreas de savana de Roraima, norte da Amazônia brasileira. As espécies Chamaecrista desvauxii (24,9%), Aeschynomene histrix (15,7%) e Galactia jussiaeana (10,8%) foram as de maior índice de valor de importância. Todas com grande abundância e ampla distribuição. Os resultados indicaram baixa densidade ou ausência de indivíduos e espécies em parcelas estabelecidas em solos mal drenados (hidromórficos). Diversidade e riqueza de espécies tendeu a ser maior em habitats formados por solos bem drenados, mais férteis e com menor concentração de alumínio trocável. É sugerido que solos pobres e sazonalmente alagados reduzam as chances de ocorrência e afetem negativamente a riqueza/diversidade de leguminosas herbáceas nas áreas de savana de Roraima.

Two new species of Janusia (Malpighiaceae) from Brazil

Two new Brazilian species of Janusia are described and illustrated: Janusia diminuta, restricted to the Restinga vegetation in Northern Rio de Janeiro State; and Janusia paraensis, which is known from the Amazonian savanna vegetation in Pará State. Their diagnostic features are pointed out and a discussion of their relations to other species of Janusia are provided herewith.

Densidade da madeira de árvores em savanas do norte da Amazônia brasileira

Densidade da madeira (DM) é uma variável importante para estimativas de estoques de carbono arbóreo em ecossistemas terrestres. Este tema é pobremente investigado em áreas de savana da Amazônia brasileira. O objetivo deste estudo foi investigar a DM das oito principais espécies arbóreas que ocorrem na savana aberta de Roraima, a maior área de savana do norte do bioma Amazônia. Foram verificadas as variações na DM em função da espécie e dos diferentes diâmetros observados ao longo da dimensão vertical de 75 indivíduos amostrados em seis sítios de coleta. Foi utilizado o método direto para obtenção de peças de madeira do fuste e da copa. Os resultados indicaram discrepância significativa interespecífica, sendo Roupala montana Aubl. a espécie de maior DM média (0,674 g cm-3). Foi detectado que existe variação significativa da DM entre as peças do fuste e da copa, independente da espécie e do sítio de coleta. A densidade da madeira de peças da copa com diâmetro entre 5 e 10 cm pode ser utilizada como preditora da DM média do indivíduo arbóreo. Nós concluimos que a DM das oito espécies arbóreas investigadas possui variabilidade interespecífica, com discrepâncias entre a DM do fuste e das partes lenhosas da copa. As distinções aqui detectadas devem ser considerados como uma importante ferramenta para melhorar as estimativas de estoque de carbono em áreas de savanas na Amazônia.

Invasion of Acacia mangium in Amazonian savannas following planting for forestry

Background : No studies have examined the invasion of exotic species used for forestry purposes in the savannas of the Brazilian Amazonia. Aims : We investigated the invasion process of Acacia mangium in savanna areas adjacent to large-scale forestry plantations in north-eastern Roraima State, Brazilian Amazonia. Methods : A tree inventory to record the presence of all A. mangium and native tree individuals was carried out in of 14 plots (each 50 m in width and 1500 m in length) established at five plantation sites. Biometric measurements were taken for all individuals to identify their structure and maturity. Distance categories were created for determining frequency of occurrence in 100 m sections along the plots for all individuals. Correlations and goodness-of-fit tests for discrete data ordered in categories were applied to verify the occurrence of A. mangium plants in relation to distance from the plantation. Results : Individuals of A. mangium were dispersed up to 900 m from the plantation edge 8–9 years after the plantation was established. Although most recorded individuals were in the juvenile stage, reproductive adults were found in two establishment patterns: non-nucleated and nucleated under native tree species. Crown cover of the savanna's most abundant native tree species facilitated the regeneration of A. mangium. Conclusions : Planting of A. mangium in Amazonian savannas provides a source of continuous dispersal, and invasion by the species is facilitated by environmental conditions.

Fire-free land use in pre-1492 Amazonian savannas

The nature and scale of pre-Columbian land use and the consequences of the 1492 "Columbian Encounter" (CE) on Amazonia are among the more debated topics in New World archaeology and paleoecology. However, pre-Columbian human impact in Amazonian savannas remains poorly understood. Most paleoecological studies have been conducted in neotropical forest contexts. Of studies done in Amazonian savannas, none has the temporal resolution needed to detect changes induced by either climate or humans before and after A.D. 1492, and only a few closely integrate paleoecological and archaeological data. We report a high-resolution 2,150-y paleoecological record from a French Guianan coastal savanna that forces reconsideration of how pre-Columbian savanna peoples practiced raised-field agriculture and how the CE impacted these societies and environments. Our combined pollen, phytolith, and charcoal analyses reveal unexpectedly low levels of biomass burning associated with pre-A.D. 1492 savanna raised-field agriculture and a sharp increase in fires following the arrival of Europeans. We show that pre-Columbian raised-field farmers limited burning to improve agricultural production, contrasting with extensive use of fire in pre-Columbian tropical forest and Central American savanna environments, as well as in present-day savannas. The charcoal record indicates that extensive fires in the seasonally flooded savannas of French Guiana are a post-Columbian phenomenon, postdating the collapse of indigenous populations. The discovery that pre-Columbian farmers practiced fire-free savanna management calls into question the widely held assumption that pre-Columbian Amazonian farmers pervasively used fire to manage and alter ecosystems and offers fresh perspectives on an emerging alternative approach to savanna land use and conservation that can help reduce carbon emissions.

Avifaunal inventory of the Amazonian savannas and adjacent habitats of the Monte Alegre region (Pará, Brazil), with comments on biogeography and conservation

Knowledge of the avifaunal composition of Amazonian savannas is important in facilitating a greater understanding of the patterns of evolution of the regional biota. Despite this, this vegetation type has been poorly sampled in comparison to adjacent rainforest habitats. The aim of this paper is to provide an avifaunal inventory of the savannas and other adjacent habitats of Monte Alegre, on the left bank of Amazon River, northwestern Pará, Brazil. Our survey is based both on our own fieldwork and on previously-collected specimens deposited in museums. A total of 300 bird species have been recorded in the region. Ninety-four species (31.3%) were restricted to a single habitat type, indicating that habitat heterogeneity is important to the overall species richness. Despite the fact that the Monte Alegre savannas present typical species restricted to this habitat, several open-country birds that occur in larger savanna areas located on the borders of Amazonia (along the Atlantic coast and close to the ‘cerrado’ boundaries) were not recorded in this area. Although Monte Alegre is species impoverished relative to other savanna regions in the Amazon basin, the Monte Alegre savannas shelter the Sulfur-breasted Parakeet (Aratinga maculata), a vulnerable species in Pará state that is only known from the Guianan area of endemism (Aleixo et al., 2011). We also comment on biogeography, taxonomy, noteworthy records, natural history and conservation of the regional avifauna.

REVISÃO DOS EFEITOS DO FOGO SOBRE A FAUNA DE FORMAÇÕES SAVÂNICAS DO BRASIL

A REVIEW ON FIRE EFFECTS ON THE FAUNA OF SAVANNA FORMATIONS IN BRAZIL. A better understanding of how species respond to fire events is of great relevance for the management and conservation of terrestrial ecosystems, especially in view of global change and increasing human activities. We present a review of papers published up to 2009 about the effects of fire on the fauna of Brazilian savanna formations (Cerrado and Amazonian savannas). Of the 1,512 papers found in the Web of Knowledge using the key words “cerrado fire*” and “savanna fire*”, only 12 deal specifically with the Brazilian fauna. In addition to these, eight other non-indexed papers or book chapters were found. Of the 20 studies, 11 were done in Brasília, indicating a concentration of the research efforts in a few areas. Faunal responses to fire are variable depending not only on species traits but also on the frequency and intensity of fires and on the spatial characteristics of the burned area such as its size and the degree of fragmentation and spatial heterogeneity of the landscape. Life-history traits, such as behavior and morphology, often determine which species are more or less susceptible to the direct effects of fire. The physical changes in habitat and/or in resource availability tend to favor some species while others are negatively affected. Fire effects tend to be more severe when there is an accumulation of fuel biomass and, consequently, a high intensity fire. The process of recolonization of the burned areas is still poorly known, but a study with galling and mining insects showed that recolonization is mainly through individuals from outside of the burned areas. Although fire in the Cerrado can cause strong but short-term changes in the structure of the vegetation, records of local extinctions of animal species are rare suggesting that at least part of the Cerrado fauna is resilient to the effects of fire. As is the case in other savannas, controlled fires in Cerrado conservation areas can be used as management tool to improve habitat diversification and thus enhance biological diversity. Keywords: Biodiversity; cerrado; fire disturbance; resource availability; wildlife management.

Non-overlap of hosts used by three congeneric and sympatric loranthaceous mistletoe species in an Amazonian savanna: host generalization to extreme specialization

Two main hypotheses predominate in the literature on mistletoe-host specificity: (1) mistletoes are only likely to specialize on plant species on which they are frequently deposited; and (2) compatibility between mistletoes and plant species is a prerequisite for mistletoe-host parasitism. I explored these hypotheses by studying the seed deposition patterns and mistletoe-host compatibility in populations of three congeneric and sympatric mistletoe species of the genus Psittacanthus (P. biternatus, P. eucalyptifolius and P. plagiophyllus - Loranthaceae). I recorded the presence or absence of these mistletoe species in 15 tree species in a savanna patch in Amazonia. Among the five tree species that I found to be potential hosts (at least one tree individual infected), I also recorded if they had at least one mistletoe seed of any species attached to their branches. Finally, I planted seeds of all mistletoe species on the same individual trees in various hosts and non-host species and recorded seed survivorship and seedling establishment within 7 (P. plagiophyllus) to 12 months (P. biternatus and P. eucalyptifolius) after planting. There was no overlap among trees used as hosts by the three Psittacanthus species. Th e most specialized mistletoe species occurred in different host tree species with low relative abundance at the study site (Psittacanthus eucalyptifolius on Vatairea macrocarpa (Benth.) Ducke, and P. plagiophyllus on Anacardium occidentale L.). Mistletoe-host compatibility, and not seed deposition patterns, was the factor most likely to explain patterns of host use by Psittacanthus species at this study site.